1. Field of the Invention
The present invention generally relates to selected phase change ink compositions containing certain polymeric dyes in combination with certain phase change ink carrier compositions.
2. Brief Description of the Related Art
In general, phase change inks are in the solid phase at ambient temperature, but exist in the liquid phase at the elevated operating temperature of an ink jet printing device. At the jet operating temperature, droplets of liquid ink are ejected from the printing device and, when the ink droplets contact the surface of the printing media, they quickly solidify to form a predetermined pattern of solidified ink drops.
The phase change inks generally comprise a phase change ink carrier composition which is combined with a phase change ink compatible colorant. Preferably, a colored phase change ink will be formed by combining the above-described ink carrier composition with compatible subtractive primary colorants. The subtractive primary colored phase change inks of this invention comprise four component dyes, namely, cyan, magenta, yellow and black. U.S. Pat. Nos. 4,889,560 and 5,372,852 teach the subtractive primary colorants employed typically may comprise dyes from the classes of Color Index (C.I.) Solvent Dyes, Disperse Dyes, modified Acid and Direct Dyes, and a limited number of Basic Dyes.
Phase change inks are desirable for ink jet printers since they remain in a solid phase at room temperature, during shipping, long-term storage, and the like. Also, the problems associated with nozzle clogging due to ink evaporation are largely eliminated, thereby improving the reliability of ink jet printing. Furthermore, in prior art phase change ink jet printers where the ink droplets are applied directly onto the printing medium the droplets solidify immediately upon contact with the substrate, migration of ink along the printing medium is prevented and dot quality is improved. This is also true of the processes and ink compositions described herein.
Separately, polymeric dyes have been used in gravure and flexographic printing industries. Specifically, as mentioned in U.S. Pat. No. 5,176,745, a specific class of polymeric dyes have been employed to make aqueous ink compositions where the polymeric dye is solubilized into the aqueous ink composition by means of a counter ion to form a soluble salt.